Polyoxyalkylene polymers having a reactive silicon group have been disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 61-141761, 61-218632, 61-233043, 1-171683, 1-279958, and 10-060253.
Room-temperature curable compositions which react with moisture in the air to cure into a rubber form are stable in storage, weather-resistant, heat-resistant, and contamination-resistant, and broadly used as sealant, adhesive, coating material, and so forth accordingly. Polyoxyalkylene polymers having a reactive silicon group are weather-resistant and suitable for sealant. However, as nice appearance is increasingly desired for housing, further enhanced weather resistance is desired.
In order to enhance the weather resistance, for example, Japanese Unexamined Patent Application Publication Nos. 61-233043 and 2001-164236 have disclosed a technique of compounding an additive-type UV absorbent or light stabilizer. However, since the additive-type UV absorbent and light stabilizer bleed to the surface, it is difficult to maintain the weather resistance over a long period.
In order to enhance the weather resistance, for example, Japanese Unexamined Patent Application Publication No. 59-122541 has disclosed a technique of blending an acrylic copolymer with a polyoxyalkylene polymer having a reactive silicon group, and says that this technique can significantly improve the weather resistance. However, it has found that long-time exposure degrades the weather resistance. Accordingly, still further enhanced weather resistance is desired.
Japanese Unexamined Patent Application Publication No. 2001-234072 has disclosed a modified silicone room-temperature curable composition containing: (A) 100 parts by weight of a modified silicone room-temperature curable polymer having a reactive silyl group and whose principal chain is polyether; (B) 0.01 to 20 parts by weight of a silane compound containing an amino group; (C) 2 to 20 parts by weight of a macromolecular UV absorbent containing 0 to 2 percent by weight of a polymerizable hindered amine compound as a constitutional unit; and (D) 0.01 to 20 parts by weight of a tin curing catalyst. Although this compound helps prevent the UV absorbent and the light stabilizer from bleeding, effectively, it does not lead to a sufficiently enhanced weather resistance, which has recently been desired.